The new university campus at ole Miss is troubled  in effloresence ;
while the more historic part is by and large free .

The resons vary ; but my humble take is the new sections have cast stone instead of limestone ;and what we are finding is that cast stone  on only 3 inches thick  becomes more and more porous over time ....limestone does to ;but it seems the cast stone holds and takes on more water ; the second culprit often is the roofing detail ;undersized scuppers and gutters ;allowing splsh back  into the brick and  masonry

Overall the most  likely culprit is the flashing detail . In the past stone was set on a bed of mortar with the lead or co[pper flshing only going partially under the stone .
Now it seems that the cast stone is set on through wall flashing ( fire and ice  shield ) then pinned with an  Rt angle bracket to its interior return and  into the brick  substrate ....and  then  set on a bed of mortar .

In the recent past 70's and 80's  this was not the case; and we see all sorts of pins and all sorts of lack of detail  that can allow water to filter in  

many new  bricks used here are hollow cavity bricks; where often the mason drops mortar into and thus creates dams for the salts to collect and travel  out in to 

I don't know about today but zinc cloride was an additive ( to make mortar harder) for early strength  that was used alot at one time . /

speaking of salts ...the doc sez I got to cut it out ....no good for me ....How come all the good stuff is "no good" for you ?  /Py




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